Method for fabricating fluid ejection device

ABSTRACT

A method for fabricating a fluid ejection device includes forming a drive circuitry layer on a substrate, fabricating at least one fluid ejection element on a top portion of the substrate, grinding the substrate from a bottom portion of the substrate up to a predetermined height, etching the top portion of the substrate to configure at least one slot within the top portion of the substrate, depositing a layer of an etch-stop material over the top portion of the substrate while filling the at least one slot with the etch-stop material, etching the bottom portion of the substrate to configure at least one fluid feed trench within the bottom portion of the substrate, removing the layer of the etch-stop material from the top portion of the substrate, and laminating a flow feature layer and a nozzle plate as a single unit over the top portion of the substrate.

CROSS REFERENCES TO RELATED APPLICATIONS

None.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

REFERENCE TO SEQUENTIAL LISTING, ETC.

None.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates generally to fluid ejection devices forprinters, and more particularly, to a method for fabricating a fluidejection device.

2. Description of the Related Art

A typical fluid ejection device (printhead) for printer, such as aninkjet printer, includes a substrate (silicon wafer) carrying at leastone fluid ejection element thereupon; a flow feature layer configuredover the substrate; and a nozzle plate configured over the flow featurelayer. The nozzle plate and the flow feature layer of the fluid ejectiondevice are generally formed as thick layers of polymeric materials.Further, the fluid ejection device includes a drive circuitry layer thatmay be made using complementary metal-oxide-semiconductor implantation.Such a drive circuitry layer is electrically coupled with the at leastone fluid ejection element, and assists in electrically connecting thefluid ejection device to the printer during use.

FIGS. 1-8 depict a typical process flow for fabrication of a fluidejection device 100. FIG. 1 depicts a substrate 110 having a top portion112 and a bottom portion 114. FIG. 2 depicts formation of a drivecircuitry layer 130 on the substrate 110. Subsequently, fluid ejectionelements 150, 170 are fabricated on the substrate 110, as depicted inFIG. 3. Each fluid ejection element of the fluid ejection elements 150,170 is electrically coupled to the drive circuitry layer 130.Thereafter, the substrate 110 is subjected to grinding from the bottomportion 114 thereof up to a predetermined height, ‘H1’ (referring toFIGS. 2 and 3). Subsequently, a planarization layer 190 (polymericlayer) is formed over the top portion 112, and particularly overselective regions (not numbered) of the top portion 112 of the substrate110, as depicted in FIG. 4. Thereafter, exposed regions (not numbered),i.e., without any planarization layer 190, of the top portion 112 of thesubstrate 110 are etched using Deep Reactive Ion Etching (DRIE)technique to form/configure at least one slot, such as slots 116, 118within the top portion 112 of the substrate 110, as depicted in to FIG.5. The at least one slot serves as a fluid via of the fluid ejectiondevice 100.

Subsequently, a layer 210 of an etch-stop material is then depositedover the exposed regions of the top portion 112 of the substrate 110while filling the slots 116, 118 with the etch-stop material, asdepicted in FIG. 6. Thereafter, the bottom portion 114 of the substrate110 is etched to form/ configure at least one fluid feed trench, such asa fluid feed trench 120, within the bottom portion 114 of the substrate110, as depicted in FIG. 7. The fluid feed trench 120 is in fluidcommunication with the slots 116, 118. Subsequently, the layer 210 ofthe etch-stop material is removed from the top portion 112 of thesubstrate 110, as depicted in FIG. 7. Thereafter, a nozzle plate 230(Photo-imageable layer) is formed over the planarization layer 190. Theplanarization layer 190 serves as the flow feature layer of the fluidejection device 100.

However, such a method of fabricating fluid ejection devices isincapable of allowing aggressive post-DRIE clean-ups while avoiding anydamage to the flow feature layers. Specifically, available DRIE etchingprocesses and strip methods are limited by the presence of the flowfeature layers and the necessity of keeping the flow feature layersintact for permanent bonding of the nozzle plates. More specifically,clean-ups after DRIE etching processes may affect the adhesion of thenozzle plates to the flow feature layers. Further, performing DRIEetching processes post formation of the flow feature layers has alsofacilitated in corrosion (manifestations such as ink ingression) of thefluid ejection devices.

In addition, application of DRIE etching processes that employhydrophobic polymers in masking and passive layers, proves to beunsuitable as the hydrophobic polymers are difficult and expensive toremove in the presence of the flow feature layers. Thus, many prior artmethods that employ such DRIE etching processes for fabricating fluidejection devices are cost-ineffective.

Accordingly, there persists a need for an efficient and a cost-effectivemethod for fabricating fluid ejection devices for printers withoutcausing any damage to flow feature layers and nozzle plates of the fluidejection devices.

SUMMARY OF THE DISCLOSURE

In view of the foregoing disadvantages inherent in the prior art, thegeneral purpose of the present disclosure is to provide a method forfabricating a fluid ejection device, by including all the advantages ofthe prior art, and overcoming the drawbacks to inherent therein.

In one aspect, the present disclosure provides a method for fabricatinga fluid ejection device. The method includes forming a drive circuitrylayer on a substrate. The method further includes fabricating at leastone fluid ejection element on the substrate. Each fluid ejection elementof the at least one fluid ejection element is electrically coupled tothe drive circuitry layer. Furthermore, the method includes forming atleast one slot within a top portion of the substrate. In addition, themethod includes forming at least one fluid feed trench within a bottomportion of the substrate. Each fluid feed trench of the at least onefluid feed trench is in fluid communication with one or more slots ofthe at least one slot. Moreover, the method includes laminating a flowfeature layer and a nozzle plate over the substrate having the at leastone slot and the at least one fluid feed trench formed therewithin.

In another aspect, the present disclosure provides a method forfabricating a fluid ejection device. The method includes forming a drivecircuitry layer on a substrate. Further, the method includes fabricatingat least one fluid ejection element on a top portion of the substrate.Each fluid ejection element of the at least one fluid ejection elementis electrically coupled to the drive circuitry layer. Furthermore, themethod includes grinding the substrate from a bottom portion of thesubstrate up to a predetermined height. In addition, the method includesetching the top portion of the substrate to form at least one slotwithin the top portion of the substrate. Moreover, the method includesdepositing a layer of an etch-stop material over the top portion of thesubstrate while filling the at least one slot with the etch-stopmaterial. Additionally, the method includes etching the bottom portionof the substrate to form at least one fluid feed trench within thebottom portion of the substrate. Each fluid feed trench of the at leastone fluid feed trench is in fluid communication with one or more slotsof the at least one slot. Further, the method includes removing thelayer of the etch-stop material from the top portion of the substrate.The method also includes laminating a flow feature layer and a nozzleplate over the top portion of the substrate having the at least one slotand the at least one fluid feed trench formed therewithin.

In yet another aspect, the present disclosure provides a fluid ejectiondevice. The fluid ejection device includes a substrate. The substrateincludes a top portion and a bottom portion; at least one slot formedwithin the top portion of the substrate; and at least one fluid feedtrench formed within the bottom portion of the substrate. Each fluidfeed to trench of the at least one fluid feed trench is in fluidcommunication with one or more slots of the at least one slot. The fluidejection device further includes a drive circuitry layer formed on thesubstrate. Furthermore, the fluid ejection device includes at least onefluid ejection element fabricated on the top portion of the substrateand electrically coupled to the drive circuitry layer. Additionally, thefluid ejection device includes a flow feature layer laminated over thetop portion of the substrate having the at least one slot and the atleast one fluid feed trench formed therewithin. Also, the fluid ejectiondevice includes a nozzle plate laminated over the flow feature layer.The at least one slot and the at least one fluid feed trench are formedwithin the substrate prior to the lamination of the flow feature layerand the nozzle plate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of the presentdisclosure, and the manner of attaining them, will become more apparentand will be better understood by reference to the following descriptionof embodiments of the disclosure taken in conjunction with theaccompanying drawings, wherein:

FIGS. 1-8 depict a prior art process flow for fabrication of a fluidejection device;

FIG. 9 depicts a flow chart illustrating a method for fabricating afluid ejection device, in accordance with an embodiment of the presentdisclosure;

FIGS. 10-15 depict a process flow for the fabrication of the fluidejection device using the method of FIG. 9;

FIG. 16 depicts a flow chart illustrating a method for fabricating afluid ejection device, in accordance with another embodiment of thepresent disclosure; and

FIGS. 17-23 depict a process flow for the fabrication of the fluidejection device using the method of FIG. 16.

DETAILED DESCRIPTION

It is to be understood that various omissions and substitutions ofequivalents are contemplated as circumstances may suggest or renderexpedient, but these are intended to cover the application orimplementation without departing from the spirit or scope of the claimsof the present disclosure. It is to be understood that the presentdisclosure is not limited in its application to the details ofcomponents set forth in the following description. The presentdisclosure is capable of other embodiments and of being practiced or ofbeing carried out in various ways. Also, it is to be understood that thephraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Further, the terms “a” and “an” herein donot denote a limitation of quantity, but rather denote the presence ofat least one of the referenced item.

The present disclosure provides a method for fabricating a fluidejection device. The fluid ejection device is in the form of a printheadfor use in printers, such as inkjet printers. The method for fabricationof the fluid ejection device is explained in conjunction with FIGS. 9and 10-15. FIG. 9 depicts a flow chart illustrating a method 10 forfabricating a fluid ejection device 300, in accordance with anembodiment of the present disclosure. FIGS. 10-15 depict a process flowfor the fabrication of the fluid ejection device 300 using the method 10of FIG. 9.

Referring to FIG. 9, the method 10 begins at 12. A substrate 310 isprovided, as depicted in FIG. 10. The substrate 310 is a silicon waferand may have a height of about 725 micrometers (μm). Without departingfrom the scope of the present disclosure, the substrate 310 may have anyshape and size as per a manufacturer's preference. Further, thesubstrate 310 may be composed of any other semi-conductor material thatis suitable for the fabrication of fluid ejection devices. The substrate310 includes a top portion 312 and a bottom portion 314. At 14, a drivecircuitry layer 330 is formed on the substrate 310, as depicted in FIG.11. Further, the drive circuitry layer 330 is formed by complementarymetal-oxide-semiconductor (CMOS) implantation, i.e., the drive circuitrylayer 330 includes CMOS drive circuitry, and is formed by techniques asknown in the art.

At 16, at least one fluid ejection element, such as fluid ejectionelements 350, 370, are fabricated on the substrate 310, and morespecifically on the top portion 312 of the substrate 310, as depicted inFIG. 12. Each fluid ejection element of the at least one fluid ejectionelement, such as the fluid ejection elements 350, 370, is electricallycoupled to the drive circuitry layer 330. The fluid ejection elements350, 370 may be heater resistors or such other elements that receiveelectrical signals from the drive circuitry layer 330 for energizationin order to eject a droplet of fluid (such as ink).

At 18, at least one slot, such as slots 316, 318, is formed within thetop portion 312 of the substrate 310, as depicted in FIG. 13.Specifically, the at least one slot is configured as a shaft that servesas a fluid via of the fluid ejection device 300, and may be formed byetching the top portion 312. More specifically, the top portion 312 maybe etched by a deep reactive ion etching (DRIE) technique. However, itwill be evident that other techniques as known in the art may be usedfor the formation of the at least one slot. Each slot of the at leastone slot may have a depth of about 60 μm. Further, the each slot mayhave a width of about 20 μm. It will be evident that the each slot mayhave any dimension, as per a manufacturer's preference.

Further, the substrate 310 may be subjected to grinding from the bottomportion 314 of the substrate 310 up to a predetermined height prior tothe formation of the at least one slot, such as the slots 316, 318,within the top portion 312 of the substrate 310. Specifically, theheight/thickness of the substrate 310 may be reduced by techniques thatare known in the art. For example, conventional grinding apparatuses maybe used for grinding the substrate 310.

At 20, at least one fluid feed trench, such as a fluid feed trench 320,is formed within the bottom portion 314 of the substrate 310, asdepicted in FIG. 14. The at least one fluid feed trench may be formedwithin the bottom portion 314 of the substrate 310 by etching, and moreparticularly, DRIE technique, the bottom portion 314. However, it willbe evident that other techniques as known in the art may be used for theformation of the at least one fluid feed trench. Each fluid feed trenchof the at least one fluid feed trench is in fluid communication with oneor more slots of the at least one slot. Specifically, the fluid feedtrench 320 is in fluid communication with the slots 316, 318. Further,the each fluid feed trench may have a width of about 300 μm. It will beevident that the each fluid feed trench may have any dimension, as per amanufacturer's preference.

Further, a layer (not shown) of an etch-stop material may be depositedover the top portion 312 of the substrate 310 while filling the at leastone slot with the etch-stop material, prior to forming the at least onefluid feed trench, such as the fluid feed trench 320, within the bottomportion 314 of the substrate 310. Etch-stop materials that are known inthe art may be utilized for the purpose of the present disclosure.Suitable examples of the etch-stop material include, but are not limitedto, a positive photoresist material, and a negative photoresistmaterial. Further, the layer of the etch-stop material may beformed/deposited over the substrate 310 using conventional techniques,such as a coating technique (spin-coating or spray-coating) and alamination process. Furthermore, such a layer of the etch-stop materialmay then be removed from the top portion 312 of the substrate 310 afterthe formation of the at least one fluid feed trench, such as the fluidfeed trench 320.

At 22, a flow feature layer 390 and a nozzle plate 410 are laminatedover the substrate 310 having the at least one slot, such as the slots316, 318 and the at least one fluid feed trench, such as the fluid feedtrench 320, formed therewithin, as depicted in FIG. 15. The flow featurelayer 390 includes at least one flow feature (fluid chamber and fluidsupply channel), such as flow features 392, 394. Each flow feature ofthe at least one flow feature is in fluid communication with one or morecorresponding slots of the at least one slot. Specifically, the flowfeature 392 is in fluid communication with the slot 316, and the flowfeature 394 is in fluid communication with the slot 318. The nozzleplate 410 includes at least one nozzle, such as nozzles 412, 414. Eachnozzle of the at least one nozzle is in fluid communication with one ormore corresponding flow features of the at least one flow feature.Specifically, the nozzle 412 is in fluid communication with the flowfeature 392, and the nozzle 414 is in fluid communication with the flowfeature 394. The flow feature layer 390 and the nozzle plate 410 may becomposed of suitable polymeric materials that are known in the art.Further, the nozzle plate 410 may be a photo-imageable nozzle plate, andmay be laminated with the flow feature layer 390 as a single unit, asdepicted in FIG. 15. However, it should be evident that the flow featurelayer 390 and the nozzle plate 410 may be laminated as separate unitsover the substrate 310.

Lamination of the flow feature layer 390 and the nozzle plate 410 overthe substrate 310 results in the fabrication of the fluid ejectiondevice 300, as depicted in FIG. 15. The method 10 ends at 24.

Another embodiment of the method for fabricating a fluid ejection device500 is explained in conjunction with FIGS. 16 and 17-23. Referring toFIG. 16, the method 30 begins at 32. A substrate 510 is provided, asdepicted in FIG. 17. The substrate 510 is similar to the substrate 310of FIG. 10, and is a silicon wafer and may have a height of about 725μm. Without departing from the scope of the present disclosure, thesubstrate 510 may have any shape and size as per a manufacturer'spreference. Further, the substrate 510 may be composed of any othersemi-conductor material that is suitable for the fabrication of fluidejection devices. The substrate 510 includes a top portion 512 and abottom portion 514. At 34, a drive circuitry layer 530 is formed on thesubstrate 510, as depicted in FIG. 18. Specifically, the drive circuitrylayer 530 is similar to the drive circuitry layer 330 of FIG. 11, and isformed on the substrate 510. Further, the drive circuitry layer 530 isformed by CMOS implantation, i.e., the drive circuitry layer 530includes CMOS drive circuitry, and is formed by techniques as known inthe art.

At 36, at least one fluid ejection element, such as fluid ejectionelements 550, 570, is fabricated on the substrate 510, as depicted inFIG. 19. Specifically, the at least one fluid ejection element isfabricated on the top portion 512 of the substrate 510. Each fluidejection element of the at least one fluid ejection element, such as thefluid ejection elements 550, 570, is electrically coupled to the drivecircuitry layer 530. The fluid ejection elements 550, 570 may be heaterresistors or such other elements that receive electrical signals fromthe drive circuitry layer 530 for energization in order to eject adroplet of fluid (such as ink).

Subsequently and after the fabrication of the at least one fluidejection element, the substrate 510 is subjected to grinding from thebottom portion 514 (back-grinding) of the substrate 510 up to apredetermined height, ‘H2’, at 38 and while referring to FIGS. 18 and19. Specifically, the substrate 510 may be back-ground to achieve afinal height of about 450 μm. Further, the height/thickness of thesubstrate 510 may be reduced by techniques that are known in the art.For example, conventional grinding apparatuses may be used for grindingthe substrate 510.

At 40, the top portion 512 of the substrate 510 is etched toform/configure at least one slot, such as slots 516, 518, within the topportion 512 of the substrate 510, as depicted in FIG. 20. Specifically,the top portion 512 may be etched by a DRIE technique. However, it willbe evident that other techniques as known in the art may be used for theformation of the at least one slot. Further, each slot of the slots 516,518 is configured as a shaft that serves as a fluid via of the fluidejection device 500, and may have a depth of about 60 μm. Further, theeach slot may have a width of about 20 μm. It will be evident that theto each slot may have any dimension, as per a manufacturer's preference.

At 42, a layer 590 of an etch-stop material is deposited over the topportion 512 of the substrate 510 while filling the at least one slot,such as the slots 516, 518 with the etch-stop material, as depicted inFIG. 21. Etch-stop materials that are known in the art may be utilizedfor the purpose of the present disclosure. Suitable examples of theetch-stop material include, but are not limited to, a positivephotoresist material, and a negative photoresist material. Further, thelayer 590 of the etch-stop material may be formed/deposited over thesubstrate 510 using conventional techniques, such as a coating technique(spin-coating or spray-coating) and a lamination process.

At 44, the bottom portion 514 of the substrate 510 is etched toconfigure/ form at least one fluid feed trench, such as a fluid feedtrench 520, within the bottom portion 514 of the substrate 510, asdepicted in FIG. 22. Further, each fluid feed trench of the at least onefluid feed trench is in fluid communication with one or more slots ofthe at least one slot. Specifically, the fluid feed trench 520 is influid communication with the slots 516, 518. Furthermore, the each fluidfeed trench may have a width of about 300 μm. It will be evident thatthe each fluid feed trench may have any dimension, as per amanufacturer's preference. At 46, the layer 590 of the etch-stopmaterial is removed from the top portion 512 of the substrate 510, asdepicted in FIG. 22.

At 48, a flow feature layer 610 and a nozzle plate 630 are laminatedover the top portion 512 of the substrate 510 having the at least oneslot (such as the slots 516, 518) and the at least one fluid feed trench(such as the fluid feed trench 520) formed therewithin, as depicted inFIG. 23. The flow feature layer 610 includes at least one flow feature(fluid chamber and fluid supply channel), such as flow features 612,614. Each flow feature of the at least one flow feature is in fluidcommunication with one or more corresponding slots of the at least oneslot. Specifically, the flow feature 612 is in fluid communication withthe slot 516, and the flow feature 614 is in fluid communication withthe slot 518. The nozzle plate 630 includes at least one nozzle, such asnozzles 632, 634. Each nozzle of the at least one nozzle is in fluidcommunication with one or more corresponding flow features of the atleast one flow feature. Specifically, the nozzle 632 is in fluidcommunication with the flow feature 612, and the nozzle 634 is in fluidcommunication with the flow feature 614. The flow to feature layer 610and the nozzle plate 630 may be composed of suitable polymeric materialsthat are known in the art. Further, the nozzle plate 630 may be aphoto-imageable nozzle plate, and may be laminated with the flow featurelayer 610 as a single unit, as depicted in FIG. 23. However, it shouldbe evident that the flow feature layer 610 and the nozzle plate 630 maybe laminated as separate units over the substrate 510.

Lamination of the flow feature layer 610 and the nozzle plate 630 overthe substrate 510 results in the fabrication of the fluid ejectiondevice 500, as depicted in FIG. 23. The method 30 ends at 50.

In another aspect, the present disclosure provides a fluid ejectiondevice, such as the fluid ejection devices 300, 500 of FIGS. 15 and 23,respectively. The fluid ejection device includes a substrate, such asthe substrates 310, 510. The substrate includes a top portion, such asthe top portions 312, 512; and a bottom portion, such as the bottomportions 314, 514. Furthermore, the substrate includes at least oneslot, such as the slots 316, 318, and 516, 518, formed within the topportion of the substrate. Also, the substrate includes at least onefluid feed trench, such as the fluid feed trenches 320, 520, formedwithin the bottom portion of the substrate. Each fluid feed trench ofthe at least one fluid feed trench is in fluid communication with one ormore slots of the at least one slot.

In addition, the fluid ejection device includes a drive circuitry layer,such as the drive circuitry layers 330, 530, formed on the substrate.Moreover, the fluid ejection device includes at least one fluid ejectionelement, such as the fluid ejection elements 350, 370, and 550, 570,fabricated on the top portion of the substrate and electrically coupledto the drive circuitry layer. Additionally, the fluid ejection deviceincludes a flow feature layer, such as the flow feature layers 390, 610,laminated over the top portion of the substrate having the at least oneslot and the at least one fluid feed trench formed therewithin. Further,the fluid ejection device includes a nozzle plate, such as the nozzleplates 410, 630, laminated over the flow feature layer. In the fluidejection device of the present disclosure, the at least one slot and theat least one fluid feed trench are formed within the substrate prior tothe lamination of the flow feature layer and the nozzle plate.

As the fluid ejection device of the present disclosure is similar to thefluid ejection devices 300, 500, accordingly, a detailed description ofthe fluid ejection device of the present disclosure is avoided hereinfor the sake of brevity.

Based on the aforementioned, the present disclosure provides aneffective method, such as the methods 10, 30, for fabricating fluidejection devices. The method employs etching (DRIE technique) prior toforming (laminating) a flow feature layer and a nozzle plate, i.e.,polymeric layers on a substrate. Therefore, etching in the absence ofany polymeric layer assists in conducting aggressive post-DRIEclean-ups. Accordingly, the present disclosure serves as a successfulattempt for performing DRIE technique prior to the formation of thepolymeric layers, while emphasizing on the potential of the sequence andthe manner in which formation of slots and/or fluid feed trenches (byetching) is accomplished prior to the lamination of the polymericlayers. Further, sequential processing of the flow feature layer and thenozzle plate assists in improving adhesion and averts any corrosion ofthe fluid ejection devices. In addition, back-grinding(thinning/reducing thickness or height) of the substrate (wafer) of thefluid ejection devices assists in improving etch exit hole accuracy anduniformity while reducing etch tilt across the substrate and reducingthe cost of DRIE technique substantially. Moreover, laminated resiststhat are used for the flow feature layer and the nozzle plate have muchbetter thickness uniformity as compared to spin-coated resists.

The foregoing description of several embodiments of the presentdisclosure has been presented for purposes of illustration. It is notintended to be exhaustive or to limit the disclosure to the preciseforms disclosed, and obviously many modifications and variations arepossible in light of the above teaching. It is intended that the scopeof the disclosure be defined by the claims appended hereto.

The invention claimed is:
 1. A method for fabricating a fluid ejectiondevice, the method comprising: forming a drive circuitry layer on asubstrate; fabricating at least one fluid ejection element on a topportion of the substrate, each fluid ejection element of the at leastone fluid ejection element being electrically coupled to the drivecircuitry layer; grinding the substrate from a bottom portion of thesubstrate up to a predetermined height; etching the top portion of thesubstrate to configure at least one slot within the top portion of thesubstrate; depositing a layer of an etch-stop material over the topportion of the substrate while filling the at least one slot with theetch-stop material; etching the bottom portion of the substrate toconfigure at least one fluid feed trench within the bottom portion ofthe substrate, wherein each fluid feed trench of the at least one fluidfeed trench is in fluid communication with one or more slots of the atleast one slot; removing the layer of the etch-stop material from thetop portion of the substrate; and laminating a flow feature layer and anozzle plate as a single unit over the top portion of the substratehaving the at least one slot and the at least one fluid feed trenchconfigured therewithin after all etching has been completed, wherein atleast a portion of the flow feature layer is laminated in a planedefined by the nozzle plate.
 2. The method of claim 1, wherein the drivecircuitry layer is formed by complementary metal-oxide-semiconductorimplantation.
 3. The method of claim 1, wherein the top portion isetched by a deep reactive ion etching technique.
 4. The method of claim1, wherein the flow feature layer comprises at least one flow feature,each flow feature of the at least one flow feature being in fluidcommunication with one or more corresponding slots of the at least oneslot.
 5. The method of claim 4, wherein the nozzle plate comprises atleast one nozzle, each nozzle of the at least one nozzle being in fluidcommunication with one or more corresponding flow features of the atleast one flow feature.